9p: implement i_op->atomic_open()
Miklos Szeredi [Tue, 5 Jun 2012 13:10:26 +0000 (15:10 +0200)]
Add an ->atomic_open implementation which replaces the atomic open+create
operation implemented via ->create.  No functionality is changed.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/9p/vfs_inode.c
fs/9p/vfs_inode_dotl.c

index 57ccb75..e8c42ce 100644 (file)
@@ -712,11 +712,14 @@ error:
 }
 
 /**
- * v9fs_vfs_create - VFS hook to create files
+ * v9fs_vfs_create - VFS hook to create a regular file
+ *
+ * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
+ * for mknod(2).
+ *
  * @dir: directory inode that is being created
  * @dentry:  dentry that is being deleted
  * @mode: create permissions
- * @nd: path information
  *
  */
 
@@ -724,76 +727,19 @@ static int
 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
                struct nameidata *nd)
 {
-       int err;
-       u32 perm;
-       int flags;
-       struct file *filp;
-       struct v9fs_inode *v9inode;
-       struct v9fs_session_info *v9ses;
-       struct p9_fid *fid, *inode_fid;
-
-       err = 0;
-       fid = NULL;
-       v9ses = v9fs_inode2v9ses(dir);
-       perm = unixmode2p9mode(v9ses, mode);
-       if (nd)
-               flags = nd->intent.open.flags;
-       else
-               flags = O_RDWR;
+       struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
+       u32 perm = unixmode2p9mode(v9ses, mode);
+       struct p9_fid *fid;
 
-       fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
-                               v9fs_uflags2omode(flags,
-                                               v9fs_proto_dotu(v9ses)));
-       if (IS_ERR(fid)) {
-               err = PTR_ERR(fid);
-               fid = NULL;
-               goto error;
-       }
+       /* P9_OEXCL? */
+       fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
+       if (IS_ERR(fid))
+               return PTR_ERR(fid);
 
        v9fs_invalidate_inode_attr(dir);
-       /* if we are opening a file, assign the open fid to the file */
-       if (nd) {
-               v9inode = V9FS_I(dentry->d_inode);
-               mutex_lock(&v9inode->v_mutex);
-               if (v9ses->cache && !v9inode->writeback_fid &&
-                   ((flags & O_ACCMODE) != O_RDONLY)) {
-                       /*
-                        * clone a fid and add it to writeback_fid
-                        * we do it during open time instead of
-                        * page dirty time via write_begin/page_mkwrite
-                        * because we want write after unlink usecase
-                        * to work.
-                        */
-                       inode_fid = v9fs_writeback_fid(dentry);
-                       if (IS_ERR(inode_fid)) {
-                               err = PTR_ERR(inode_fid);
-                               mutex_unlock(&v9inode->v_mutex);
-                               goto error;
-                       }
-                       v9inode->writeback_fid = (void *) inode_fid;
-               }
-               mutex_unlock(&v9inode->v_mutex);
-               filp = lookup_instantiate_filp(nd, dentry, generic_file_open);
-               if (IS_ERR(filp)) {
-                       err = PTR_ERR(filp);
-                       goto error;
-               }
-
-               filp->private_data = fid;
-#ifdef CONFIG_9P_FSCACHE
-               if (v9ses->cache)
-                       v9fs_cache_inode_set_cookie(dentry->d_inode, filp);
-#endif
-       } else
-               p9_client_clunk(fid);
+       p9_client_clunk(fid);
 
        return 0;
-
-error:
-       if (fid)
-               p9_client_clunk(fid);
-
-       return err;
 }
 
 /**
@@ -910,6 +856,93 @@ error:
        return ERR_PTR(result);
 }
 
+static struct file *
+v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
+                    struct opendata *od, unsigned flags, umode_t mode,
+                    bool *created)
+{
+       int err;
+       u32 perm;
+       struct file *filp;
+       struct v9fs_inode *v9inode;
+       struct v9fs_session_info *v9ses;
+       struct p9_fid *fid, *inode_fid;
+       struct dentry *res = NULL;
+
+       if (d_unhashed(dentry)) {
+               res = v9fs_vfs_lookup(dir, dentry, NULL);
+               if (IS_ERR(res))
+                       return ERR_CAST(res);
+
+               if (res)
+                       dentry = res;
+       }
+
+       /* Only creates */
+       if (!(flags & O_CREAT) || dentry->d_inode) {
+               finish_no_open(od, res);
+               return NULL;
+       }
+
+       err = 0;
+       fid = NULL;
+       v9ses = v9fs_inode2v9ses(dir);
+       perm = unixmode2p9mode(v9ses, mode);
+       fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
+                               v9fs_uflags2omode(flags,
+                                               v9fs_proto_dotu(v9ses)));
+       if (IS_ERR(fid)) {
+               err = PTR_ERR(fid);
+               fid = NULL;
+               goto error;
+       }
+
+       v9fs_invalidate_inode_attr(dir);
+       v9inode = V9FS_I(dentry->d_inode);
+       mutex_lock(&v9inode->v_mutex);
+       if (v9ses->cache && !v9inode->writeback_fid &&
+           ((flags & O_ACCMODE) != O_RDONLY)) {
+               /*
+                * clone a fid and add it to writeback_fid
+                * we do it during open time instead of
+                * page dirty time via write_begin/page_mkwrite
+                * because we want write after unlink usecase
+                * to work.
+                */
+               inode_fid = v9fs_writeback_fid(dentry);
+               if (IS_ERR(inode_fid)) {
+                       err = PTR_ERR(inode_fid);
+                       mutex_unlock(&v9inode->v_mutex);
+                       goto error;
+               }
+               v9inode->writeback_fid = (void *) inode_fid;
+       }
+       mutex_unlock(&v9inode->v_mutex);
+       filp = finish_open(od, dentry, generic_file_open);
+       if (IS_ERR(filp)) {
+               err = PTR_ERR(filp);
+               goto error;
+       }
+
+       filp->private_data = fid;
+#ifdef CONFIG_9P_FSCACHE
+       if (v9ses->cache)
+               v9fs_cache_inode_set_cookie(dentry->d_inode, filp);
+#endif
+
+       *created = true;
+out:
+       dput(res);
+       return filp;
+
+error:
+       if (fid)
+               p9_client_clunk(fid);
+
+       filp = ERR_PTR(err);
+       goto out;
+}
+
 /**
  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
  * @i:  inode that is being unlinked
@@ -1488,6 +1521,7 @@ out:
 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
        .create = v9fs_vfs_create,
        .lookup = v9fs_vfs_lookup,
+       .atomic_open = v9fs_vfs_atomic_open,
        .symlink = v9fs_vfs_symlink,
        .link = v9fs_vfs_link,
        .unlink = v9fs_vfs_unlink,
@@ -1502,6 +1536,7 @@ static const struct inode_operations v9fs_dir_inode_operations_dotu = {
 static const struct inode_operations v9fs_dir_inode_operations = {
        .create = v9fs_vfs_create,
        .lookup = v9fs_vfs_lookup,
+       .atomic_open = v9fs_vfs_atomic_open,
        .unlink = v9fs_vfs_unlink,
        .mkdir = v9fs_vfs_mkdir,
        .rmdir = v9fs_vfs_rmdir,
index e3dd2a1..a354fe2 100644 (file)
@@ -230,7 +230,6 @@ int v9fs_open_to_dotl_flags(int flags)
  * @dir: directory inode that is being created
  * @dentry:  dentry that is being deleted
  * @mode: create permissions
- * @nd: path information
  *
  */
 
@@ -238,9 +237,16 @@ static int
 v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
                struct nameidata *nd)
 {
+       return v9fs_vfs_mknod_dotl(dir, dentry, omode, 0);
+}
+
+static struct file *
+v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
+                         struct opendata *od, unsigned flags, umode_t omode,
+                         bool *created)
+{
        int err = 0;
        gid_t gid;
-       int flags;
        umode_t mode;
        char *name = NULL;
        struct file *filp;
@@ -251,19 +257,25 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
        struct p9_fid *dfid, *ofid, *inode_fid;
        struct v9fs_session_info *v9ses;
        struct posix_acl *pacl = NULL, *dacl = NULL;
+       struct dentry *res = NULL;
 
-       v9ses = v9fs_inode2v9ses(dir);
-       if (nd)
-               flags = nd->intent.open.flags;
-       else {
-               /*
-                * create call without LOOKUP_OPEN is due
-                * to mknod of regular files. So use mknod
-                * operation.
-                */
-               return v9fs_vfs_mknod_dotl(dir, dentry, omode, 0);
+       if (d_unhashed(dentry)) {
+               res = v9fs_vfs_lookup(dir, dentry, NULL);
+               if (IS_ERR(res))
+                       return ERR_CAST(res);
+
+               if (res)
+                       dentry = res;
+       }
+
+       /* Only creates */
+       if (!(flags & O_CREAT) || dentry->d_inode) {
+               finish_no_open(od, res);
+               return NULL;
        }
 
+       v9ses = v9fs_inode2v9ses(dir);
+
        name = (char *) dentry->d_name.name;
        p9_debug(P9_DEBUG_VFS, "name:%s flags:0x%x mode:0x%hx\n",
                 name, flags, omode);
@@ -272,7 +284,7 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
        if (IS_ERR(dfid)) {
                err = PTR_ERR(dfid);
                p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
-               return err;
+               goto err_return;
        }
 
        /* clone a fid to use for creation */
@@ -280,7 +292,7 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
        if (IS_ERR(ofid)) {
                err = PTR_ERR(ofid);
                p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
-               return err;
+               goto err_return;
        }
 
        gid = v9fs_get_fsgid_for_create(dir);
@@ -345,7 +357,7 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
        }
        mutex_unlock(&v9inode->v_mutex);
        /* Since we are opening a file, assign the open fid to the file */
-       filp = lookup_instantiate_filp(nd, dentry, generic_file_open);
+       filp = finish_open(od, dentry, generic_file_open);
        if (IS_ERR(filp)) {
                err = PTR_ERR(filp);
                goto err_clunk_old_fid;
@@ -355,7 +367,10 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
        if (v9ses->cache)
                v9fs_cache_inode_set_cookie(inode, filp);
 #endif
-       return 0;
+       *created = true;
+out:
+       dput(res);
+       return filp;
 
 error:
        if (fid)
@@ -364,7 +379,9 @@ err_clunk_old_fid:
        if (ofid)
                p9_client_clunk(ofid);
        v9fs_set_create_acl(NULL, &dacl, &pacl);
-       return err;
+err_return:
+       filp = ERR_PTR(err);
+       goto out;
 }
 
 /**
@@ -982,6 +999,7 @@ out:
 
 const struct inode_operations v9fs_dir_inode_operations_dotl = {
        .create = v9fs_vfs_create_dotl,
+       .atomic_open = v9fs_vfs_atomic_open_dotl,
        .lookup = v9fs_vfs_lookup,
        .link = v9fs_vfs_link_dotl,
        .symlink = v9fs_vfs_symlink_dotl,